So I was sitting in the bank drivethu yesterday and I thought somebody was running a jack hammer next to me...nope just suby. I can make this nasty drone/gravel/vibration come and go by adjusting the tension on the alt belt. I took the belt off and spun the alt by hand...seemed to spin free and easy but I'm not sure what it is supposed to feel like. With the belt tensioned just enough to not slip, the noise is barely there. Seeing as it's saturday and my mechanic is sleeping I come to you all for help. Btw everything I own is in the car and I'm homeless in SLC, again. TIA.

Knowing what year/model might help a bit.

 

 

If it's a Legacy thypically the harmonic balancer runs BOTH accessory belts (PS and alt/AC comp).

If you dont have a mechanical stetoscope, take a long screwdriver or extension and put on end on the alt near the bearing and then on the engine near the balancer. With the other end on your ear, you'll find out fast where the noise is coming from.

ok. sorry. I'm a bit frazzled pneumonia and homeless and car-less = stress.

 

95 legacy 5sp 145k.

 

I guess im not sure exactly what the harmonic balancer is. Is this the outer pulley that the belt for the alt and ps is on?

 

I like the idea of listening to it but where to put the screwdriver to listen to the balancer...isn't it spinning?

Sorry about your circumstances.

 

Assuming it's not a problem with the alt, there are a couple of possibilities related to the crank pulley. Make sure that its bolt is properly tightened -- it's not uncommon for it to be insufficiently torqued when work such as timing belt replacement has been done, and for it to further loosen as it runs. If loose, the pulley and key can be damaged, but much worse is that the crankshaft itself can as well.

 

Another possibility with the crank pulley is deterioration of the rubber that couples the two pieces of it. Initially that doesn't typically cause a vibration, but rather a squealing sound.

A search should turn this stuff up.

 

The "harmonic balancer" is also the "crankshaft pulley". It does have a rubber section between the bolt in the middle that goes into the crankshaft and the 2 places on the outside that drive the accessory belts.

 

Read it again. He's telling you to put the screwdriver on the ALTERNATOR - actually both ends of it. You can't check the harmonic balancer by listening with a screwdriver. However often if it's seperating (or loose) you can see it wobble when the car is running.

 

Answered while OBW99 was answering so some duplication.

Just to try something different (in addition to good stuff above), if you push in the clutch to the floor, does the gravel noise change?

I suspect the noise you are hearing is coming from a bad bearing in the belt tensioner. See if the pulley movement is sloppy or noisy. I had a bad one at one time and just found a replacement bearing at a place that sells bearings. The dealer will sell you the whole part.

Edited October 3, 200916 yr by Cougar

Thanks. I want to vote for the alternator now. With the belt off and free spinning the alternator there is a noticeable wobble in the alternator pulley. New alternators come with a new pulley?

Yes, they do.

yes they do. Tested the alternator at napa and it failed. Replaced. Sounds Sweet now. Added bonus, disconnecting the battery reset the cel for rear o2 sensor. Thanks everybody. Anybody need a roomate in SLC? lol.

Considering your situation, try a local wrecking yard for a replacement alternator. Much less expensive than new (our Pull a Part yard charges under $20 for an alternator) but make sure you get a 30 day return warranty so you can be sure you get a chance to test out your replacement.